Most alpine plants show xeromorphic features which help reduce water loss. Small holes can be seen in the tip of the tiny veins known as Hydathodes. Leaves that possess many hairs or pubescence will have larger boundary layers; the hairs serve as mini-wind breaks by increasing the layer of still air around the leaf surface and slowing transpiration rates. Only a very little part of transpiration takes place by this process. Water Less amount of soil water decreases the rate of transpiration.
With water hanging on the cut end of the shoot transfer it to the Potometer. Root-Shoot Ratio The efficiency of absorbing roots and evaporating surfaces shoots affect the rate of transpiration. Guttation Guttation is similar to transpiration, but there are differences too. The entire process of water movement through a plant is included in the definition of transpiration, but this term most specifically refers to the final step in which leaf tissue releases liquid water into the atmosphere as water vapor. Structure of leaves :Thick cuticle, waxy coating on leaves, sunken stomata, covering of dead hair on leaves decreases transpiration.
Then take the polythene bag out and put some Anhydrous Copper Sulphate to inside the bag. Scientists have found the only function of Hydathodes is the Guttation. Humidity Humidity is the concentration if water vapour in the air. For transpiration to occur, water vapor leaving the stomata must diffuse through this motionless layer to reach the atmosphere where the water vapor will be removed by moving air. When atmospheric pressure is high, the rate of transpiration is low. In the daylight period the stomata gets opened and that causes to increase in the rate of transpiration.
Conversely the lower the relative humidity of the outside atmosphere the higher will be the rate of transpiration. If the rate of transpiration exceeds the rate of absorption, the stomata get closed the cells lose their turgidity and the plant wilts. Decreased root growth increases resistance of water absorption which results in partial stomatal closure. Leaves can only perform photosynthesis, the process by which plants make food from sunlight, when stomata are open and thus allowing carbon dioxide, which is needed for photosynthesis, to enter the leaf. During a growing season, a leaf will transpire many times more water than its own weight. As in temperature, transpiration is increased in high light intensity and is decreased in low light intensity.
It also includes a process called guttation, which is the loss of water in liquid form from the uninjured leaf or stem of the plant, principally through water stomata. Humidity Spray water on the leaves and cover the plant with wet cloth. Example: Light an incense stick. Instead wax should be used. Plants can alter the size of their boundary layers around leaves through a variety of structural features. Therefore, the rate of transpiration decreases when the humidity of the atmosphere increases.
It also increases the capacity of the air to absorb more water. As ambient temperature rises, leaves attempt to maintain appropriate internal temperatures by increasing the amount of moisture that evaporates through the stomata. If rate of transpiration exceeds rate of absorption, a water stress condition develops and rate of transpiration is reduced. Temperature - increased temperature increases transpiration as the water has a greater kinetic energy and … so there is more evaporation of water. Effect of Atmospheric Pressure Water vapour pressure decreases as the atmospheric pressure decreases with increasing altitude.
But the leaves constitute major portion of stomata. Light also increases the permeability of the cell membrane, making it easy for water molecules to move out of the cell. It is the reason why you can see water droplets at the tip of leaf blades. Atmospheric pressure : In low atmospheric pressure, the rate of transpiration increases. High humidity means the air around the leaves is already saturated and has a higher concentration of water molecules than inside the leaves. There are different factors that can affect the rate of transpiration as discussed below.
Types of Transpiration Transpiration in plants is essentially of three types. External or Environmental Factors i Light: There is a close relationship between the opening of stomata and presence of light. As a result of wide opening of stomata, the saturated interior cells of leaf arc exposed to the outer atmosphere. This process known as the Guttation. These factors also affect the stomatal movements.
Some plants which grow in arid regions, such as cacti and succulents, conserve precious water by transpiring less water as compared to coastal plants. Stomata — Stomata are pores in the leaf that allow gas exchange where water vapor leaves the plant and carbon dioxide enters. The transpiration is faster in mild wind. In the case of the plants such as Opuntia and Asparagus the leaf is modified into thorns and the stem becomes flattened and green to perform the function of the leaf. This reduces the water loss and helps the plant to survive in adverse conditions.